The invention relates to a driving roll stand for a continuous casting plant, in particular a multi-strand continuous casting plant for billets, comprising two rolls arranged one above the other, at least one of which is drivable by means of a rotary drive. The lower roll is mounted on a support supported on a base, and the upper roll is mounted on a lever hinged to the support and pivotably movable by means of an adjustment drive.
A driving roll stand of this kind is known from German Auslegeschrift No. 1,758,398. There, a separate pressure-medium cylinder is provided at each side of the stand for the pivotal movement of the lever at the height of the strand guideway, which pressure-medium cylinders, on the one hand, are hinged to the lever and, on the other hand, are hinged to the base plate of the support. The rotary drive for the upper roll is supported at one of the necks of the upper roll.
The arrangement of the two pressure-medium cylinders laterally beside the strand guideway, in addition to causing a relatively great width of the stand, necessitates the provision of heat protection shields. The utilization of this known construction with multi-strand continuous casting plants, in which there exists the problem of guiding the strands as closely adjacent as possible, is unfavorable because of the great width and because of the poor accessibility to the pressure-medium cylinders. In particular, it is possible only with great difficulty to exchange a pressure-medium cylinder at several driving roll stands arranged close to one another, or to repair the same, since manipulations have to be carried out between the driving roll stands while they continue to be in operation. A further disadvantage of this known construction is to be seen in that the total weight of the rotary drive has to be accommodated by the neck of the roll, which constitutes a great strain on the bearings of the driving rolls. The slight distance between the rotary drive and the strand, owing to the rotary drive being directly arranged at the neck of the roll, makes it necessary to provide a heat shield.
Moreover, it is known to adjust the pivotable lever of the driving roll stand by means of only a single pressure-medium cylinder laterally arranged. The disadvantages of such a design are to be seen in the fact that, because of the eccentrically active cylinder force the pivotable lever of the driving roll stand is torsionally strained, and thus has to be constructed to be accordingly stiff so as to resist torsion. The torsion-stiff design of the lever, however, requires it to be heavily constructed. Besides, it is not ensured with this construction that the rolls are exactly parallel.